national road; national highway
Refers to a road designated and managed at the national level; often appears in route names such as 国道一号 or in phrases like 国道沿い.
国道沿いに大きな道の駅がある。
There is a large roadside station along the national highway.
国道一号を走って東京へ向かった。
We headed for Tokyo on National Route 1.
National Route 1 connects Tokyo to Osaka.
There's a large shopping mall along the national highway.
We kept driving along the national highway until late at night.
国道 is a regular national highway with intersections and traffic lights, whereas 高速道路 is a controlled-access expressway you enter and exit via ramps.